Echo5Bravo

1990 Limited - Operating temp 235 degrees... WTF?

It is the fully pressurized system... with no radiator cap... just the pressurized puke tank.

So far I have replaced the puke tank, the water pump, the thermostat (then reinstalled the old one), flushed the system (myself) and put in new coolant. My operating temp is still around 235 (as the gauge reads).

Despite having a 195 degree thermostat, I can see the temp gauge needle rise to about 215, then dip when the thermostat opens (this is the same with two separate thermostats, so I ruled out a bad thermostat).
Even with a 20 degree margin of error on the gauge, I'm still running hot.

The only strange thing I can find is that while running at 235 degrees I can squeeze the hose that connects the block (just off the thermostat) to the top (intake) of the radiator and it will not be full of fluid... it won't be tight with pressure... it feels mostly empty. Also, the same hose is hotter near the thermostat than near the radiator. Somehow, I am not getting proper flow through in the coolling sysytem.

I have tried disconnecting that hose at the block, filling it with fluid, then quickly re-attaching it... still running hot.

Please, for the love of Pete, help a brother out.

Thanks.
E5B

MulishaXJman

This is way out there, but make sure your new water pump has the proper rotation for your application..

Good Luck

Programbo

This may sound odd but perhaps you can temporarily replace the hoses with clear water hose (Cheap and easy to get at Home Depot by the foot)..That way you can actually see how well the coolant is flowing to and from various areas and pin point a potential problem area.

Echo5Bravo

Good thinking. I might try that if someone on the forum doesn't recognize this problem and have the magic bullet for me.

Thanks.

thevervaeckes

It sounds like you have a air pocket in the system. Does your heater work? Your heater core maybe plugged. have you checked the temp with another gauge? Good luck and let us know what you find out.

c-loss

I had the smae problem. I changed over to an open system out of a newer xj. I chased my air pocket and chased it somemore. The sealed systems just suck to bleed if you ask me. I changed over and installed another temp gauge. My gauge on the dash is off by about 20 degrees to. That might help you out. It cost me about 75 bucks with pulling the radiator out of a friends jeep the new heater valve.
HTH
Corey

Echo5Bravo

Thanks for the replies. The problem has been fixed. I posted a similar plea for help on the NAXJA forum as well. The feed back there was similar, most pointed to an air bubble in the system... which turned out to be correct.
The solution:
First, I partially drained the system, removed the thermostat and drilled two small holes in the flange, one at the 12 O'clock pos and one at the 6 o'clock pos, then reinstalled it.
Next I parked nose-down, let it cool, and removed the temp sensor on the DS rear of the block. I refilled the pressure bottle until fluid came out, then put the sensor back in. Topped off the bottle, closed everything up and drove it around the block about 15 times. Operating temp = 210. I'll take it!
Thanks again, Fellas.
Take 'er easy.
E5B